1. Field of the Invention
The present invention relates to a three-dimensional display apparatus and a backlight module thereof; particularly, the present invention relates to a three-dimensional display apparatus capable of providing multidirectional stereoscopic images and a backlight module thereof.
2. Description of the Prior Art
As the market for stereoscopic visual effect is growing, the applications of three-dimensional display are continuously increased in different fields, such as television, desktop monitor, notebook computer, portable devices, camera, etc. Three-dimensional technique utilizes two offset images separately for two eyes of the viewer to combine a stereoscopic image. Traditionally, the display apparatus capable of generating stereoscopic visual effect differs in two major groups: requiring special glasses and requiring no special glasses. The display apparatus requiring no special glasses is classified into two types: (1) disposing a light splitting film at exterior of the display panel to sequentially providing images generated by the display apparatus separately to the right eye and the left eye; (2) disposing light splitting structures inside the backlight module to allow the light from the backlight module is directionally split to produce images respectively at the right eye and the left eye after light passing through the display panel.
FIG. 1A illustrates the backlight module used in the second type of display apparatus requiring no special glasses. As shown in FIG. 1A, the backlight module 10 includes a light guide plate 30, a first light source 71, and a second light source 72. Prismatic structures 50 are disposed on the light guide plate 30 along the long axis of the light guide plate 30. The first light source 71 and the second light source 72 are disposed at two opposite sides of the light guide plate 30 to alternatively emit light perpendicular to the extension direction of the prismatic structures 50 into the light guide plate 30. Lights from the first light source 71 and the second light source 72 will be split by the prismatic structures 50 to respectively produce intensity peak areas 81 and 82 in a direction parallel to the long axis of the light guide plate 30, as shown in FIG. 1B. In other words, when the viewer's eyes are parallel to the long axis of the light guide plate 30, the left eye and the right eye will receive lights from the first light source 71 and the second light source 72, respectively. Therefore, the viewer's left eye and right eye may be aware of different images that are combined to provide the stereoscopic visual effect.
However, in the above design, when the display apparatus is rotated to a vertical position, (i.e. viewer's eyes are vertical to the long axis of the light guide plate 30) the distribution direction of the intensity peak areas 81 and 82 will be perpendicular to the viewer's eyes. As such, the viewer's left eye and right eye will not respectively receive the predetermined images and the stereoscopic visual effect no longer exist.